Scientists have made significant progress towards building the first complex artificial life from scratch.
In a package of seven papers published Thursday in the U.S. journal Science, researchers from the Synthetic Yeast Genome Project (Sc2.0) announced that they have successfully synthesized five new yeast chromosomes, meaning that 30 percent of a key organism's genetic material has now been swapped out for engineered replacements.
By the end of this year, this international consortium, led by geneticist Jef Boeke of the New York University, hoped to have designed and built synthetic versions of all 16 chromosomes, the structures that contain DNA, for the one-celled microorganism, Baker's yeast.
Baker's yeast have long served as an important research model because their cells share many features with human cells, but are simpler and easier to study.
Meanwhile, yeast's ability to grow quickly has made it an effective platform on which to grow useful materials, such as in production of the Hepatitis B vaccine, anti-malaria medicine and biofuel.
"This work sets the stage for completion of designer, synthetic genomes to address unmet needs in medicine and industry," Boeke said in a statement.
In March 2014, Sc2.0 successfully assembled the first synthetic yeast chromosome, synIII, comprising 272,871 base pairs, the chemical units that make up the DNA code.
The new round of papers consisted of an overview and five papers describing the first assembly of synthetic yeast chromosomes synII, synV, synVI, synX, and synXII. A seventh paper provided a first look at the 3D structures of synthetic chromosomes in the cell nucleus.
As the first Chinese team involved in this project, Tianjin University's team, led by Professor Yingjin Yuan, has finished the completed synthesis of synV and synX, and developed an efficient repairing technique for point mutation.
In addition, Tsinghua University's team, led by Junbiao Dai, has synthesized the longest chromosome synXII.
Furthermore, researchers at BGI, the leading Chinese genomics organization, and Britain's University of Edinburgh, finished the synthesis of synII.
An in-depth analysis found that the resulting synII strain shows a viability that is highly similar to the wildtype strain.
According to the researchers, the design plan for the Sc2.0 genome is about eight percent smaller than the natural yeast genome, with noncoding "junk" DNA removed and other genetic sequences relocated that can make DNA unstable and prone to mutations.
Patrick Cai, professor of the University of Edinburgh and international coordinator for the Sc2.0 consortium, said: "We are excited to mark this milestone in our quest to create an entire organism from scratch."
Professor Paul Freemont, co-director of the Center for Synthetic Biology and Innovation at the Imperial College London, said this work represents "an amazing advance in our ability to chemically synthesise the blue print of life."
"From these and other recent advances, it is clear that the technology for genome synthesis is maturing to such an extent that researchers are looking for future genome synthesis projects which also includes the human genome," Freemont said.
"It is therefore essential that an open and transparent debate is initiated on the merits of future genome synthesis projects such that informed decisions can be made as to their benefits and risks."
